JPS6147055B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improving the material of metal graphite brushes (gold-graphite, silver-graphite, copper-graphite, etc.).
The purpose is to increase mechanical strength.

In general, metal graphite brushes are made by adding additives such as molybdenum disulfide, lead, boron nitride, and tungsten disulfide to the main components of metal (e.g., gold, silver, copper, etc.) and graphite, and then forming the brush into powder. Created by

The characteristics of brushes made only of metal and graphite change greatly depending on the surrounding environmental conditions, and their friction characteristics are particularly poor under low humidity, causing them to stick to or slip against the commutator (or slip ring), causing damage to the commutator (or slip ring). Frictional force changes over time. As a result, the brush vibrates, making electrical contact with the commutator unstable, generating large sparks between the brush and the commutator, and causing the brush to wear out considerably.
In addition, because of the strong adhesion with the commutator, there are drawbacks such as short-circuiting accidents are likely to occur.

Therefore, in order to eliminate these drawbacks, the above-mentioned additives are added.Molybdenum disulfide improves the friction properties at low temperatures, and boron nitride/tungsten disulfide improves the friction properties at high temperatures. , improves the friction characteristics and electrical contact of the brush. Furthermore, since lead has the property of not bonding with copper, which is the main component of the commutator (or slip ring), the adhesion between the brush and the commutator can be reduced.

However, these additive particles have almost no bonding ability with the metal/graphite brush main raw material particles;
Molybdenum disulfide and tungsten disulfide are easily broken due to their self-wall-opening property, and as a result, the brush structure becomes brittle, the mechanical strength decreases, and the brush wear increases. Therefore, the amount of additives is currently limited to about 1%.

In the present invention, additive particles are plated with metal in order to increase the mechanical strength of the brush without sacrificing the benefits of adding such additives.

The diameter of the additive particles 1 is approximately 1 to 100 μm, and a metal plating 4 having a thickness of approximately 0.1 to 10 μm is applied to the surface thereof. This plating is performed, for example, by a known chemical plating method. Copper, silver, gold, etc. are used for the plating metal.

When the above metal-plated particles of additive 1 are added to the brush main raw material particles of metal 2 and graphite 3 as shown in Figure 2, additive 1 is added to the metal-plated layer 4 on the surface.
By this, the bonding property with the metal particles 2 and graphite particles 3 is enhanced. Additionally, the additives are also well bonded to each other through the metal plating layer 4. Furthermore, even if the internal additive particles themselves are broken, since they are covered with the plating layer 2, the bonding properties with the main raw material particles and the bonding properties between the additive particles will not deteriorate.

Therefore, even if the amount of Additive 1 is increased to 5, 10, or 20%, the brush structure will not become brittle.
This has the effect of making it possible to obtain a high-performance brush with high mechanical strength.

In addition, as the metal plating layer 4 of many additives is worn out one after another due to use, the additive itself becomes interposed between the brush and the commutator, which improves the brush's frictional characteristics, electrical contact, and adhesion. The original intended effects such as reduction can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway perspective view of the additive, and FIG. 2 is an internal structure diagram of a brush of the present invention which is powder-molded using the additive. 1 is an additive, 2 is a metal, 3 is graphite, 4 is a metal plating layer, and 5 is a pore.

Claims (1)

[Claims] 1. Particles of molybdenum disulfide, lead, boron nitride, tungsten disulfide, etc., which are added to the brush raw material consisting of powder particles of metal and graphite to improve the friction characteristics and electrical contact of the brush, are combined with copper and silver. - A powder-formed metal graphite brush characterized by being plated with metal such as gold.